BACKGROUND: Nosocomial infections cause significant patient morbidity and mortality. The 2.5 million nosocomial infections that occur each year cost the US healthcare system $5 million to $10 million. Staphylococcus aureus has long been recognized as an important pathogen in human disease and is the most common cause of nosocomial infections. OBJECTIVE: To describe the epidemiology of S. aureus nosocomial infections that are attributable to patients’ endogenous colonization. DATA SOURCES: Review of the English-language literature and a MEDLINE search (as of September 1997). DATA SYNTHESIS: The ecologic niche of S. aureus is the anterior nares. The prevalence of S. aureus nasal carriage is approximately 20–25%, but varies among different populations, and is influenced by age, underlying illness, race, certain behaviors, and the environment in which the person lives or works. The link between S. aureus nasal carriage and development of subsequent S. aureus infections has been established in patients on hemodialysis, on continuous ambulatory peritoneal dialysis, and those undergoing surgery. S. aureus nasal carriers have a two- to tenfold increased risk of developing S. aureus surgical site or intravenous catheter infections. Thirty percent to 100% of S. aureus infections are due to endogenous flora and infecting strains were genetically identical to nasal strains. Three treatment strategies may eliminate nasal carriage: locally applied antibiotics or disinfectants, systemic antibiotics, and bacterial interference. Among these strategies, locally applied or systemic antibiotics are most commonly used. Nasal ointments or sprays and oral antibiotics have variable efficacy and their use frequently results in antimicrobial resistance among S. aureus strains. Of the commonly used agents, mupirocin (pseudomonic acid) ointment has been shown to be 97% effective in reducing S. aureus nasal carriage. However, resistance occurs when the ointment has been applied for a prolonged period over large surface areas. CONCLUSIONS: Given the importance of S. aureus nosocomial infections and the increased risk of S. aureus nasal carriage in patients with nosocomial infections, investigators need to study cost- effective strategies to prevent certain types of nosocomial infections or nosocomial infections that occur in specific settings. One potential strategy is to decrease S. aureus nasal carriage among certain patient populations. KEY WORDS: nasal carriage, nosocomial infection, Staphylococcus aureus. Ann Pharmacother 1998;32(suppl):S7-16. IN THE US, more than 2.5 million nosocomial infections oc- cur each year, and a significant percent contribute to or cause morbidity, mortality, and death. 1 The Centers for Disease Control and Prevention (CDC) estimates that nosocomial infections contribute to 0.7–10.1% of deaths and cause 0.1–4.4% of deaths occurring in hospitals. These infections cost the US healthcare system at least $5 million annually. Under systems that use a capitated reimburse- ment structure such as diagnostic-related groups, the costs related to nosocomial infections are frequently not recov- ered, and thus represent a loss to the institution or healthcare system. 2,3 In 1992, nosocomial infections added an average of 4 extra hospital days to the patient’s length of stay and $2100 to the patient’s hospital bill. 1 Burgeoning medical care costs, efforts directed at reducing these costs, and recognition of the contributing morbidity and mortality of nosocomial infections have pushed prevention and, hence, control of nosocomial infections into the forefront. Staphylococcus aureus has long been recognized as an important pathogen in human disease. Between 1986 and 1996, S. aureus was the most commonly isolated pathogen causing nosocomial infections reported to the National Nosocomial Infection Study (NNIS) at the CDC. 4 Further- more, NNIS data show that methicillin-resistant S. aureus (MRSA) rates have increased over fourfold from 1982 un- til 1991, the increase being most prominent in hospitals with more than 500 beds. 5 Steinberg et al. 6 reviewed S. au- reus community- and nosocomially acquired bacteremias from 1980 to 1983 and 1990 to 1993 and found that both methicillin-susceptible and -resistant S. aureus bacteremia rates doubled. The potential increase in S. aureus infec- tions, particularly in hospital settings, has led many investi- gators to reevaluate the epidemiology of the organism and rethink prevention strategies in patients who are hospital- ized or undergoing medical procedures. Since the late 1950s, numerous studies have linked S. aureus nasal carriage with an increased S. aureus infection risk. 7-14 The body of literature that establishes the link be- The Annals of Pharmacotherapy ■ 1998 January, Volume 32 ■ S7 New Approaches to Reduce Staphylococcus aureus Nosocomial Infection Rates: Treating S. aureus Nasal Carriage Trish M Perl and Jonathan E Golub Trish M Perl MD MSc, Assistant Professor, School of Medicine, Johns Hopkins University, Baltimore, MD; and Hospital Epidemiologist, Department of Hos- pital Epidemiology and Infection Control, Johns Hopkins Hospital Jonathan E Golub MPH, School of Hygiene, Johns Hopkins University Reprints: Trish M Perl MD MSc, Department of Hospital Epidemiology and Infec- tion Control, 425 Osler, 600 N. Wolfe St., Johns Hopkins Hospital, Baltimore, MD 21287, FAX 410/614-0888, E-mail tperl@welchlink.welch.jhu.edu at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from at Huazhong University of Science and Technology on October 11, 2013 aop.sagepub.com Downloaded from